The third 5-year period of this project will concentrate on energy mobilization by mosquitoes in the laboratory (Project 1) and by mosquito populations in the field (Project 2). The laboratory study will be with mosquitoes whose food intake and energy expenditure will be closely monitored to establish the relationship of a lifetime's energy budget to potential longevity, fecundity and flight. The field study will be a series of mark-release-recapture experiments designed to establish actual longevity, fecundity and dispersal as a function of blood and sugar intake, in turn affected by physiological state and environmental conditions. These projects will limit their studies to Culex nigripalpus and Wyeomyia vanduzeei. Ancillary studies will be of appetential flight or mosquito flight pathways (Project 3) and of Wyeomyia life tables (Project 4). The effect of several population characteristics on vectorial capacity, aside from simple density, will be assessed.